Tempe, Arizona 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

588
FXUS65 KPSR 192310
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
410 PM MST Thu Mar 19 2026

.UPDATE...
Updated Aviation...

&&

.KEY MESSAGES...

- A historic March heatwave will produce record shattering lower
desert high temperatures exceeding 100 degrees through at least
early next week.

- An Extreme Heat Warning is in effect across southeast California
and the Arizona deserts through Sunday.

- The unprecedented afternoon heat will be dangerous, especially
with any strenuous or long-duration outdoor activities without
proper hydration and taking breaks in the shade, or air conditioning.

&&

.SHORT TERM /TODAY THROUGH FRIDAY/...
An unprecedented March heatwave is a result of a record strong high
pressure ridging for this time of year, of which current 500 mb RAP
analysis places the center over the CA-NV-AZ Tri-State area.
Analyzed H5 heights have already tipped into a 595-596 dam range
with ensembles in good agreement that the strength of the ridge will
peak around 597 dam. Although the strength of the ridge will wane
Friday and the weekend, strong anti-cyclonic subsidence should
remain relatively stationary (other than a slight eastward drift)
over the Desert Southwest, allowing for lower level thermal profiles
to rapidly warm and develop a very warm airmass across the region.
This airmass may prove difficult to dislodge or even modify by a
meaningful amount heading into next week.

Forecast highs across the lower deserts will range from around 100F-
106F today and 102F-108F Friday - likely the peak of this event.
These forecast highs represent values around 25F above daily normals
and 7F-10F above daily records (see Climate section). Widespread
moderate HeatRisk is anticipated, with even low-end major HeatRisk
for some areas on Friday. Due to the unprecedented nature of this
heatwave, the timing coinciding with a weekend, and many out-of-
state visitors and folks not acclimated to this level of heat, this
event will be quite impactful. Extreme Heat Warnings are already in
effect for much of the the forecast area, and will remain in effect
through Sunday. Remember to stay hydrated, take frequent breaks in
the shade or in air conditions spaces if you are planning outdoor
activities, and check on your family, friends, and neighbors. This
can be a dangerous level of heat for those not taking proper
precautions and for those that are sensitive to the heat.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
A few pieces of shortwave energy in the northern stream are
advertised by ensembles passing overtop the ridge this weekend,
acting to dampen heights aloft and dislodge the initial anticyclone
east of the region. However, lower tropospheric temperatures do not
have time to respond by Saturday, and NAEFS mean H8 temperatures
well in excess of CFSR climatological maximum values for mid-late
March should support highs similar to what is forecast today. By
Sunday, forecast highs fall more into a 99F-102F range, then likely
1F-2F cooler Monday, but still flirting with the triple digits for
many of the typically hotter lower desert locales. Ensembles mean H5
heights bottom out around 582-585 dam sometime Sunday into Monday,
still in excess of the 97th percentile of climatology.

During the middle of next week, the trend in the last few forecast
packages has been for warmer temperatures as another strong yet more
transient ridge forms under an anticyclonically curved jet streak.
Though the ridging should be lower amplitude compared to the current
ridge, and anticyclonic subsidence will be shorter lived (likely
peaking in its influence sometime Tuesday), H5 heights are still
shown to rise into a 587-590 dam range. This will support a gradual
warming into the middle of the upcoming workweek, with coverage of
100F+ temperatures increasing yet again. All this is to say that
confidence is growing in a longer duration heatwave, with highs
remaining between 15F-25F above daily normals and breaking daily
records well into next week.

&&

.AVIATION...Updated at 2310Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and
Southeast California/Southwest Arizona including KIPL and KBLH:

No significant weather issues will exist through Friday evening
under mostly clear skies. The behavior of winds will be nearly
identical to the past 24 hours featuring speeds largely under 10kt,
and directional shifts occurring near the typical times.

&&

.FIRE WEATHER...
A historic high pressure will lead to record temperatures, very dry
conditions, seasonal winds, and mostly sunny skies into this
weekend. High temperatures will be around 25 degrees above normal
through Saturday before gradually dropping off Sunday and Monday.
Abnormally hot and very dry conditions will translate to MinRH
readings of 5-10% through the next 7 days. Overnight recoveries will
be poor, with values between 15-35% through Saturday night.
Humidities improve slightly early next week primarily for valley
locations in the western deserts like the Yuma area, lower Colorado
River Valley, Imperial Valley, and lower Gila River Valley,
especially with respect to overnight recoveries.

&&

.CLIMATE...

Daily record highs through early next week:

Date      Phoenix         Yuma         El Centro
----      -------         ----         ---------
3/19     96 in 2017     98 in 2017     96 in 2017
3/20     96 in 2017     99 in 2004     98 in 2004
3/21     97 in 2004    102 in 2004    100 in 2004
3/22     94 in 1990     98 in 2004     96 in 2004
3/23     93 in 1990     96 in 1990     93 in 1990
3/24     96 in 2025     97 in 2025     96 in 2025
3/25     99 in 2025     99 in 1896     99 in 2025

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Sunday for AZZ530.

     Extreme Heat Warning until 8 PM MST Sunday for AZZ531>555-559-
     561.

CA...Extreme Heat Warning until 8 PM PDT Sunday for CAZ561>570.

&&

$$

SHORT TERM...Whittock
LONG TERM...Whittock
AVIATION...18
FIRE WEATHER...Whittock/Berislavich
CLIMATE...18/Kuhlman